The research proposed in this program will investigate the nature of selected human cognitive functions, their disorders, and their neural basis. It will test patients with single strokes for their abilities to recognize and remember words and objects, and will correlate their deficits with the neural systems affected by their lesions. It approaches this research with concepts and techniques developed in cognitive science, cognitive neuroscience, and human neuroimaging. The program is an outgrowth of the applicants' previous research and the more recent development of collaborations among them. The program contains four scientific projects and one core. Project 1 deals with word recognition, project 2 with visual object recognition, project 3 with implicit memory for words and objects, and project 4 with the MR correlates of these disturbances. Patient recruitment, screening, and triage will take place in the Administrative and Clinical Core. The projects in the program are closely related at multiple levels of inquiry. At the most abstract level, the three projects share a common conceptual framework, derived from contemporary cognitive science and cognitive neuroscience. There are many specific interactions between the three cognitively-oriented projects with respect to hypotheses and patients to be tested. All the projects are designed to identify the location of the neural systems that underlie the operation of the processors involved in the cognitive functions under investigation. Because of these shared features, the program as a whole affords the opportunity to consider issues that could not be addressed in any one project alone. This program-project application is part of a major effort on the part of the Massachusetts General Hospital and associated institutions to develop an integrated research and clinical program in cognitive neuroscience. The researchers assembled in this program have a long-term commitment to take advantage of the features of the local environment and of the support by M.G.H. of research in this area, to create a program in which this undertaking can flourish.